Analysis of lip flow in trumpet playing using iterative adaptive inverse filtering

Gustavo Machado OliveiraDavi Alves MotaMaurício Alves Loureiro

Introduction

● The lip vibration is the source of the trumpet’s sound. Its control is considered very important● The sound production on the trumpet happens when the lips vibrate in contact with the mouthpiece

of the instrument● The vibration produces the opening and closing movement of the lips which allows the passage of

small portions of air● It is difficult to analyze lip vibration because of the contact of the lips with the mouthpiece when

playing

Source-Filter Model

We used the source-filter model approach to voice production for estimating the airflow passing through the player’s lips at the mouthpiece

Inverse Filtering

● Method commonly used in voice research (glottal flow)● Applies the inverse of the source-filter model to estimate the excitation signal

The Experiment

● We selected the seven notes of the harmonic series of the primary tube of the instrument (all pistons closed), produced by the seven vibration modes of the instrument, as shown in figure above

● Two trumpet players with different technical and musical skills were recruited, one with experience in orchestra playing, the other in trumpet teaching

● We recorded this melodic line from a trumpet in C and in B-flat● They played theses notes on both, trumpet in C and in B-flat

Data Processing - Segmentation

● Note segmentation was processed with the use of Audacity software● We used the Matlab implementation of the inverse filtering algorithm proposed by Alku (1992),

Iterative Adaptive Inverse Filtering (IAIF)● The algorithm resample to 10.000 Hz, in order to remove noise from the high register. A window of

100 samples (10 milliseconds) was selected, where the signal presented the highest spectral stability.

The Lip Flow

Estimation of the lip flow after applying the algorithm

The Lip Flow

One cycle of the lip flow obtained from the trumpet sound signal. This cycle was performed by one of the research participants

Discussion - Skewness and Kurtosis

In speech production studies, skewness and kurtosis measures are generally used to analyze the behavior of glottal flow

Discussion - Skewness and Pitch

Boxplot of skewness for each harmonic tube from both participants and instruments together (trumpet in C and B-flat). The continuous line shows a strong positive correlation of skewness to the harmonic tube.

Discussion - Kurtosis and Pitch

Boxplot of kurtosis for each harmonic tube for both participants and instruments together (trumpet C and B-flat). The continuous line shows a kurtosis correlation to tube harmonics. Kurtosis values show a strong negative correlation to note pitch.

Discussion - Median Absolute Deviation

The median absolute deviations of skewness and kurtosis for each harmonic tube.

Conclusions

● The method here proposed presents potentials for modelling trumpet sound production and estimating the lip flow, which could be used as a non-invasive method for trumpet performance technique analysis.

● Results showed that the duration of the opening of the lips changes considering with note pitch: higher negative skewness values tend to higher positive skewness values as note pitch increase. It was also possible to observe that higher notes might demand higher lip control skills.

● Further tests are necessary to verify the application of this methodology under different performance conditions.

References

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Analysis of Lip Flow in Trumpet Playing Using Iterative Adaptive Inverse FilteringGustavo Machado Oliveiragustavomacholi@gmail.comDavi Alves Motadavialvesmota@gmail.comMaurício Alves Loureiromauricio.alves.loureiro@gmail.com